JUPITER, Fla. — Mike Stanton hadn’t played for four weeks. The 21-year-old outfielder — who hit 22 homers in just 359 at-bats in his rookie season last year — had been sidelined since straining his quad on Feb. 27 in an exhibition game against a college team, a contest in which Stanton had smashed a homer in his first trip to the plate.

The Marlins outfielder looked rusty in his first trip to the plate, swinging and missing badly at Clay Buchholz‘ offerings en route to a strikeout. In his subsequent trips to the plate, however, he made his mark…literally.

Stanton crushed a pair of three-run homers against Buchholz in his next two at-bats, one on a hanging changeup, another on a cutter that backed over the plate. The first shot was prodigious, clanging about halfway up the Roger Dean Stadium scoreboard in left-center field, the sort of moonshot that is rarely seen.

The blast was impressive enough in its own right, but even more so given that the stiff breeze was blowing out to right field throughout the day. On the day, Stanton was 3-for-4 with two homers while driving in seven, and giving a glimpse of why he is so highly regarded throughout the game, including by the Sox.

“He’s a giant. He’s a big boy, man. He’s not afraid to swing, obviously. But he’s a big strong kid,” said Sox catcher Jarrod Saltalamacchia after his first glimpse of the Marlins outfielder. “He puts it in the air, it’s going to go somewhere.”

At the 2008 trade deadline, when the Sox were exploring deals in which they would part with Manny Ramirez, one of the teams with whom they were engaged was the Marlins. They discussed a number of scenarios with Florida, including some scenarios in which the Sox would have tried to negotiate a multi-team deal that would have netted them both outfielder Jason Bay from the Pirates as well as prospects from the Marlins.

The Sox had targeted Stanton (then destroying Single-A pitchers for 39 homers) as the top prospect in the Marlins’ system at the time, so his name came up in talks. But the Marlins knew what they had in the 2007 second-round selection, and so they were uninterested in parting with Stanton, according to sources familiar with the negotiations. And so it was instead the Dodgers who ended up becoming the partner in a three-way transaction that sent Ramirez to Los Angeles, Bay to Boston and four prospects (Craig Hansenand Brandon Moss from the Red Sox, and Andy LaRoche and Bryan Morris from the Dodgers) to Pittsburgh.

Instead, the Red Sox can now have only rare glimpses of his jaw-dropping power, as was the case on Thursday.

Stanton’s prospect stock rose to the point where he was rumored to be the centerpiece of a complicated three-way deal that would have sent Manny Ramirez to the Marlins, brought both Stanton and Jason Bay to the Sox and sent an assortment of players to Pittsburgh. A National League source, however, said that while the Marlins received plenty of inquiries about Stanton, he was never available in a deal, even for Ramirez. The potential was too great for Florida to contemplate parting with the outfielder.